Electronic publishing and print-on-demand applications have become increasingly popular in recent years. In such operations, a high-speed electronic printer, also commonly termed a “laser printer” is employed to produce printed pages that are thereafter bound into books of appropriate size and shape. Contemporary electronic printers, and the peripheral sheet-utilization devices that accompany them, are capable of providing duplex-printed (e.g. two-sided) sheets that can be folded-over and interleaved into a bound book, or otherwise cut and stacked to form a bound book. Where large-size sheets are employed (for example 14½-inch by 22½-inch sheets) a plurality of pages can be printed on a single sheet. The sheet is then subsequently cut and/or or folded into a completed book in the appropriate page order.
It is often desirable to feed individual sheets, including large-scale sheets adapted for book folding, into a sheet-feed electronic printer. However, it is also desirable, for increased efficiency, to derive the individual sheets from a continuous roll of paper web. Thus, the web is initially fed from a driven roll stand to a downstream cutter, where sheets of the desired length are cut from a web of predetermined width. In some implementations, the web may be slit along its length to derive two or more narrower sheets as well. The individual sheets are then passed into electronic printer. One example of a sheet feeder, which passes individual sheets into a printer is shown and described in the U.S. Pat. No. 5,818,470, entitled SYSTEM AND METHOD FOR DIRECTLY FEEDING PAPER TO PRINTING DEVICES, by Crowley, and related patents thereto, the teachings of which are expressly incorporated herein by reference. This patent describes a technique for feeding sheets to a stack-feed port of a printer or other utilization device based upon the demand for sheets by the stack feeder of the device. However, contemporary printers/utilization devices often contain dedicated sheet feed port that issues a request signal to provide sheets from the cutter to the port.
One particular concern in the preparation and binding of books is the grain direction of the paper. When paper is produced, it defines a grain direction that typically corresponds to the direction which the paper flows through the paper making process. To achieve the highest quality for the finished book, the sheets should be printed with a uniform grain direction, and the finished book should provide all pages with a similar grain direction. Since the grain direction of the roll may differ from that desired for the folded pages, maybe appropriate to rotate the sheets prior to feeding them into the electronic printer. In the past, this is entailed stacking the cut sheets into a feed stack, rotating the feed stack and then feeding the rotated stack of sheets to the feed port of the electronic printer. Clearly, this is a slower and less efficient process that requires additional human effort and may be prone to mistakes.
There are many other reasons that the user may desire the ability to rotate sheets and directly feed such sheets to a printer or other utilization device without resorting to the creation of an intermediate feed stack. For example, the web may be more efficiently cut in one orientation, by preferably fed in an orthogonal orientation to the cut orientation.
Rotation of sheets for a high-volume, high-speed handling application “on-the-fly” from a cutter is a challenging problem. Each sheet must be positively rotated to a substantially orthogonal orientation from its cut orientation without error—otherwise a jam or misfeed will occur. Feed rates in excess of 125-200 sheets-per-minute may be required. However, the rotator should preferably enable the handling a wide range of sheet dimensions, and optionally disable the rotation functionality when not needed.
It is, thus, desirable to provide a sheet-feeding arrangement that includes a novel system and method for rotating sheets before they are fed from a web cutter to an electronic printer or other sheet-utilization device. This system and method should allow relatively large-sized sheets (for example, up to approximately 14½ by 22½ inches) to be fed reliably with the proper rotation so as to account for grain direction and other dimensional requirements. The system and method should accommodate a range of sheet sizes and dimensions with easy adjustability therebetween. Such a system and method should provide a device that is easy to service and affords long-term reliability.